Experimental Study On Silicon Carbide Neutron Detector

With the development of global economy,energy crisis and climate change have become more and more serious.Low carbon,safe and high-efficient nuclear energy can meet the future energy demand and contribute to the sustainable development of economy.In recent years,the fourth-generation advanced reactors have attracted much attention due to their excellent neutron economy,inherent safety,sustainable development and nuclear nonproliferation.In order to ensure the stable operation of the reactor and the safety of personnel and environment,it is necessary to monitor the neutron flux in the reactor.However,the reactor is a harsh environment with high temperature and intense radiation,and the traditional neutron detector is difficult to meet the requirements for neutron flux.Silicon carbide?SiC?detector is based on the third-generation semiconductor SiC material developed in recent years.It has the characteristics of wide band gap and large displacement threshold energy,and can withstand the neutron monitoring under high temperature and intense radiation environment.In this paper,the neutron detection performance and gamma ray response of 4H-SiC neutron detector are studied by Monte Carlo simulation software Geant4 and experimental test.The main contents of this paper are as follows:The first chapter is the introduction.This chapter introduces the background of the fourth-generation advanced nuclear reactors system and the function of the neutron monitoring system in the reactor,and describes the excellent characteristics of high temperature and radiation resistance of 4H-SiC neutron detector and the research status at home and abroad,which lead to the research contents of this subject.The second chapter is the theoretical basis of 4H-SiC neutron detector.This chapter introduces the structure,principle of neutron detection and performance indexes of 4H-SiC neutron detector,which provide theoretical basis for the research.The third chapter is the simulation of 4H-SiC neutron detector.This chapter introduces the Monte Carlo simulation software Geant4,the geometry,particle source,reaction process and information collection process of 4H-SiC neutron detector in Geant4 simulation software.Referring to the neutron and gamma radiation fields in molten salt reactor,the structural parameters of 4H-SiC neutron detector suitable for molten salt reactor are calculated by Geant4 simulation software.The thickness of ⁶LiF conversion layer is 25?m and the thickness of 4H-SiC sensitive layer is 80?m.In addition,the neutron detection efficiency of 4H-SiC neutron detector under ²⁵²Cf neutron source is calculated to be 0.16%,and the neutron detection efficiency is 0.23%after being moderated by 6cm polyethylene.The energy depositions of gamma ray produced by ⁶⁰Co source in 4H-SiC neutron detector are calculated.The fourth chapter is the experimental study of 4H-SiC neutron detector.In this chapter,the experimental platform and scheme of 4H-SiC neutron detector are introduced,and the experimental results in the standard radioactive source are also introduced.The detection performance of 4H-SiC neutron detector is tested by ²⁵²Cf standard source and ⁶⁰Co standard source.The calculation results show that the neutron detection efficiency of 4H-SiC neutron detector is consistent with the simulation results,it has a good linear relationship between counting rates with neutron flux.The energy depositions of gamma ray produced by ⁶⁰Co source in4H-SiC neutron detector are less,so the neutron and gamma can be discriminated by setting energy threshold.The fifth chapter is the summary and prospect.This chapter summarizes the main research results of this paper,the future research direction is also proposed.